Apparatus for extruding metal sheath or pipe



' July 9, 1940; G SEELEY 2,206,977

APPARATUS FOR EXTRUDING METAL SHEATH OR PIPE Filed Nov. 20, 1937 INVENTOR GZASEELEV ATTORNEY Patented July 9, 1940 APPARATUS FOR Ex'rnUnmG METAL SHEATH on I'IPE George Allen Seeley, Baltimore, Md., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application November 20, 1937, Serial No. 175,611

2 Claims. (01. 207-17) This invention relates to apparatus for extruding metal sheath or pipe, and more particularly 11) apparatus for extruding lead sheath for ca An object of the invention is to provide apparatus for facilitating the control of the concentricity and uniformity of extruded metal pipe or sheathing.

In accordance with one embodiment of the invention, the lead is first extruded through a tapering annular orifice of decreasing cross section, then through an annular orifice parallel to the axis of the core being covered, but spaced therefrom from where the netal passes into a 5 conical aperture, reducing the diameter of the sheath, and thence through a sizing opening. The behavior of the metal during these steps is controlled by a control of the temperature of the me al. l

A complete understanding of the invention may be had .by reference to the following description, taken in conjunction with the accompanying drawing, in which Fig. 1 is a cross-sectional view of an extrusion head embodying theinventio'n;

Fig. 2 is an enlarged cross-sectional view of the die showing a portion of the core tube; and

Fig. 3 is a fragmentary end view of the die looking in the direction of the arrows- 3-3 in Fig. 2.

Referring now more in detail to the drawing,

a die block '6 is shown which receives heated plastic lead from an extrusion cylinder not shown. Mounted in the die block is an inner die mem- 5 her or core tube loo-operating with a die 8 to modifications may be made therein without deform the lead around a core of insulated conductors or the like. The die is held in place by means of a threaded outlet memberll.

When pressure is exerted on the plastic lead in the extrusion chamber, it is forced into a tapering annularorifice l2 whose cross-section diminishes toward the outlet end of the die. This chamber produces a gradual reduction in the sheath being formed and aids in holding the core tube 1 concentrically in the die.

tricity of the sheath are determined. From the annular space of passage It the sheath passes into a portion "of the die opening in which the walls taper inwardly toward the outlet end of the die to'uniformly reduce the diameter of the tion..

From'the opening l2 the sheath being formed passes into sheath. The temperature of the metal being extruded is so controlled that the space between,

the wall l4 and the core does not fill up; in other words, the metal is sufiiciently rigid at this point so that its only increase in thickness is due to 5 the reduction in the diameter of they sheath. From this portion of the die opening the sheath passes through a sizing opening whose walls are parallel to the axis of the sheath and core.

The temperature of the metal in the die dur- 10 ing the extrusion process is controlled by pass-' ing steam or other suitable cooling medium through the die. A steam supply pipe I6 is connected to a; passage 11 in the die holding member H and connects to a passage 3 in the'die.

From the passage Hi the cooling medium enters an annular passage l9 circulating around the die to a connecting passage 2| which connects with a second annular passage 22. From the passage 22 the cooling medium enters a con- 20 necting passage 23 and passes into a third annular passage 24. From the passage 24 the cooling medium is conducted to'a final annular passage 25 from which the steam escapes-around the exterior of the sheathed cable through the 25 die holding member II which has a larger internal diameter than the external diameter of the sheathed cable. This cooling system insures the proper cooling of the metal in the extrusion die and in conjunction with the die produces a 30 cable of uniform concentricity and weight.

It will be understood that the nature and embodiment of the invention hereindescribed is merely illustrative and that many changes and 35 parting from the spirit and scope of the inven- What is claimed is: u 1. In a metal sheath extruding apparatus, an 10 extruding head for receiving plastic metal under pressure, a die member having an internal diameter greater than the external diameter of a core to be sheathed, -a coretube co-operating with said die member to form a'tapering annular 45 orifice,. a second tapering annular-orifice of smaller diameter, both diminishing toward the outlet end of said die member, a third annular orifice between said first-named orifices the walls of which are parallel'to and spaced away from 5 the axis of a sheath to be formed, a fourth and final sizing orifice for uniformly controlling the diameter of said sheath, and means for controlling the temperature of said sheath by the circulaTtion of a cooling medium comprising a pm 5 rality of annular passages in the said die member 2. In a metal sheath extruding apparatus, an extruding head for receiving plastic metal from a source, a die member having an internal diameter greater than the external diameter of a cable to be sheathed, a core tube co-oper- ,ating with said die member to form a tapering annular orifice diminishing toward the outlet end of said die member, a second annular orifice the walls of which are parallel to and spaced away from the axis of a sheath to be formed, a third orifice diminishing toward the extruded sheath, the final passage being near-' est to and discharging around the exterior of lo the completed extruded sheath.

GEORGE ALLEN SEELEY. 

